A liquid crystal display (LCD) device generally comprises a backlight module and a liquid crystal panel, and has advantages of thin, low drive power and low power consumption over other display devices and has been widely used in industries of display devices. Presently, backlight modules are mainly sorted into light-emitting-diode (LED) backlight modules and cold-cathode-fluorescent-lamp (CCFL) backlight modules. Since a light-emitting-diode backlight module has an advantage of low power consumption, hence using the light-emitting-diode backlight module to replace the cold-cathode-fluorescent-lamp backlight module is now a main development trend of backlight module industries.
Based on a modular concept, most of light-emitting-diode backlight modules now install a plurality of light-emitting diodes in a light bar. Before installation, finished products of light-emitting diodes will be classified by a predetermined standard, wherein the basis for classification may be brightness, chromaticity, wavelength or forward voltage of the light-emitting diodes. Because a backlight module is required to offer a uniform light source, therefore only light-emitting diodes classified in a certain bin will be chose for installing in the light bar. Therefore, light-emitting diodes that are practically used have a low proportion of the total number of products, so that manufacturing cost of backlight module is relatively increased.
Furthermore, the light-emitting diodes in the light-emitting-diode light bars that are presently used in a backlight module are all arranged with an identical pitch. When the light bar is driven to emit lights, the light-emitting diodes in a center of the light bar inevitably will not be easy to dissipate heat compared with the light-emitting diodes in two ends of the light bar. Since temperature difference greatly affects luminous efficiency of a light-emitting diode, phenomenon of uneven heat distribution will affect the uniformity of overall luminescence of the backlight module, and also the work life of the light-emitting diodes in the center of the light bar are relatively shorter.
Hence, it is necessary to provide a backlight module to overcome the problems existing in the conventional technology.